The present invention relates to a control system for docking a marine vessel.
Today's marine vessels are often equipped with a plurality of propulsion units, for example three, for driving the vessel. If every propulsion unit is associated to a separate control lever the handling of the vessel can be unnecessarily complicated. As many users of marine vessels are not experienced helmspersons, a simplified control system is desirable.
WO 2007/05995 describes a control system for a set of propulsion units where a centrally arranged propulsion unit of the set is controlled as a slave based on control signals provided by at least one of the remaining propulsion units of the set. Thereby, the number of control levers are decreased, for example from three to two, thus the control system for the vessel is simplified.
However, there is always a desire to even further simplify the handling of a marine vessel, for example by means of introducing further improvements to the control system for controlling a set of marine propulsion units.
It is desirable to achieve a control system for a set of marine propulsion units, and a marine vessel with such a control system that is further simplified.
The inventor has observed that if the drivelines are paired so that only two steering angles are used to control the propulsion units, namely a first angle for port side propulsion units and a second for the starboard side propulsion units, the yaw and sway movements counteract against each other. The invention is based on the inventor's realization that simultaneous control of yaw and sway movements can be achieved through a control system for a set of propulsion units where two propulsion units achieve yaw movement and two propulsion units achieve a sway movement.
According to a first aspect of the inventive concept, a marine propulsion control system for controlling a set of propulsion units carried by a hull of a vessel, wherein said set of propulsion units comprise a first, a second, a third, and a fourth propulsion unit, said marine propulsion control system comprising a control unit configured to receive an input command from a steering control instrument for operating the vessel, determine a desired delivered thrust, gear selection and steering angle for said first, second, third and fourth propulsion unit respectively, based on the input command, and provide a set of control commands for controlling the desired delivered thrust, gear selection and steering angle for said first, second, third and fourth propulsion unit, wherein if said input command simultaneously indicates a sway and yaw input command said control unit is configured to simultaneously provide at least a first control command to said first and fourth propulsion units and a second control command to said second and third propulsion units, wherein said first control command is adapted to achieve a sway movement of the marine vessel and said second control command is adapted to achieve a yaw movement of said marine vessel.
In the context of this application a “vessel” should interpreted as any type of vessel, such as larger commercial ships, smaller vessel such as leisure boats and other types of water vehicles or vessels.
Furthermore, in the context of this application “gear selection” should be interpreted as selection of rotation direction of the propeller, i.e. forwards or rearwards rotation direction.
Moreover, in the context of this application the terms “sway”, “yaw” and “surge” for vessel movements are used. “Sway” is a linear lateral movement, Le, port or starboard movements, “yaw” is when the vessel rotates about a vertical axis and surge is a linear longitudinal movement, i.e. forward or reverses movements.
Through the system described, the propulsion units can he controlled individually. Thereby the propulsion units may for example be switched independently between a forward propulsion state and a reverse propulsion state and steered independently of one another.
A common solution to facilitate the handling of a vessel in slow speed is to equip the marine vessel with additional propulsion units for the specific purpose of maneuvering the marine vessel at low speeds, such as docking. However, that is a costly solution which increase the total cost of the vessel significantly. The solution presented herein does not affect the total cost of the vessel in the same extend, as the regular propulsion units can be used for handling sway and yaw movements of the vessel.
By said control system, the sway movement does not have to rely on inertia from an earlier sway operation when achieving a yaw, Instead, both a sway and a yaw thrust can be provided at the same time by separating the control of the propulsion units in two channels, where one channel comprises commands for achieving the vessel to sway, and the other channel comprises commands for achieving the vessel to yaw. Each of the channels comprising control commands for at least two propulsion units.
Many inexperienced operators compare operating a marine vessel to operating a land vehicle, e.g. a car, and one of the hardest things to learn is how the marine vessel drifts due to inertial effects, wind and currents, which require the operators to plan their movements long in advance. By allowing the operator to simultaneously moving the vessel in a both a sway and yaw movement the handling of the vessel is vastly facilitated, since an operator of the vessel does not have to plan the vessels movements in several steps.
There are basically four possible combinations of sway and yaw movements for a vessel. All combinations may be accomplished by two propulsion units performing the sway movement and two other propulsion units simultaneously performing the yaw movement.
In the examples below the movements are achieved by four propulsion units, a first propulsion unit arranged as a port side propulsion unit, a second propulsion unit arranged as a port center propulsion unit, a third propulsion unit arranged as a starboard center propulsion t. and a fourth propulsion unit arranged as a starboard side propulsion unit.
The first combination is a port sway and a clockwise yaw. To achieve that movement the port side propulsion unit is set to have a reverse gear selection and a steering angle pointing outwardly from a longitudinal axis, thus providing a thrust with at least a component in the port direction. In the context of this application “a longitudinal axis” should be interpreted as an axis extending from the vessel's bow to the vessel's stern substantially creating a center line that divides the vessel's hull into two substantially symmetrical mirrored portions,
Moreover, the port center propulsion unit is set to have a forward gear selection and performing a thrust with at least a force component in parallel to the longitudinal axis and directed towards the how. Further, the starboard center propulsion unit is set to have a reverse gear selection and performing a thrust with at least a component in parallel to the longitudinal axis and directed from the bow. Finally, the starboard propulsion unit is set to have a forward gear selection and a steering angle pointing outwardly from the longitudinal axis, thus providing a thrust with at least a component in the port. direction.
Thereby, the port and starboard propulsion unit will sway the vessel in a port movement and the port center and starboard center propulsion unit will yaw the vessel in a clockwise direction.
The other combinations of sway and yaw movements can be achieved, by simply altering the gear selection (forward/reverse) of the four propulsion units, which will be described in detail later. Moreover, there are of course also combinations of movements where the desired movement of the vessel is a combination of sway, yaw and surge movements, which also will be discussed later.
According, to another embodiment, the second and third propulsion units are intermediately provided between said first and fourth propulsion unit. If the second and third propulsion units are used for achieving a yaw movement of the vessel their steering angle may be substantially parallel with the longitudinal axis. By being intermediately provided between the first and fourth propulsion unit the space around the stern is used most efficiently. If the two propulsion units provided as center propulsion units would be used fix achieving a sway, the propulsion units would have to be provided with more space between them, as the propulsion units achieving a sway need to be non parallel to the longitudinal axis.
According to yet another embodiment, the first and fourth propulsion units steering angles are substantially inverted relative a longitudinal axis.
In one embodiment of the invention the first and fourth propulsion unit angles are set to outwards angles compared to the longitudinal axis.
By utilizing the two outer propulsion units, i.e. the first and fourth propulsion unit, for achieving the sway movement the propulsion units can be set to have an outwards angle without interfering with an adjacent propulsion unit. Thereby, a larger steering angle relative the longitudinal axis can be set for the first and fourth propulsion units. Thereby a component force in the lateral axis achieving a sway movement of the vessel is provided.
In another embodiment the first and fourth propulsion unit angles are set to a substantially maximum outwards angle. Thereby, the component force in the lateral axis achieving a sway movement of the vessel is maximize.
In yet another embodiment the steering angles of the second and third propulsion units are substantially the same. In one embodiment, the steering angles of the second and third propulsion units are substantially parallel to the longitudinal axis in a horizontal plane. Thereby, the thrust provided by the second and third propulsion units are directed along a longitudinal axis, thus affecting the yaw movement but not the sway movement of the marine vessel.
According to yet another embodiment, the first control command to said first and fourth propulsion units is configured to set one of said first and fourth propulsion units in a forward gear selection and the other one in a reverse gear selection. Thereby, the force components parallel to the longitudinal axis may be zero, thus leaving a force component parallel to a lateral axis that will achieve a sway movement of the vessel. If a surge movement is also desirable, the force component parallel to the longitudinal axis may be larger than zero.
According to another embodiment of the inventive concept the second control command to said second and third propulsion units is configured to set one of said second and third propulsion units in a forward gear selection and the other one is in a reverse gear selection. Thereby, the force components parallel to the longitudinal axis ma be set to zero by adjusting the thrust of the second and third propulsion units, thus leaving a moment force for achieving a yaw without moving the vessel in a surge movement.
According to yet another embodiment, the marine propulsion control system further comprises four independent ECUs for providing, an interface between said control unit and said first, second, third and fourth propulsion unit respectively. Thereby, the control unit does not have to comprise an interface for communicating with the first, second and third propulsion unit, Moreover, existing ECUs in a marine vessel can be utilized.
According to another embodiment of the inventive concept the second control command to said second and third propulsion units is configured to set one of said first and fourth propulsion units in a forward gear selection and the other one is in a reverse gear selection. Thereby, the force components parallel to the longitudinal axis may be set to zero by adjusting the thrust of the second and third propulsion units, this leaving a moment force for achieving a yaw without moving the vessel in a surge movement
According to vet another embodiment, the marine propulsion control system further comprises four independent ECUs for providing, an interface between said control unit and said first, second, third and forth propulsion unit respectively. Thereby, the control unit does not have to comprise an interface for communicating with the first, second and third propulsion unit. Moreover, existing ECUs in a marine vessel can be utilized.
According to yet another embodiment, the four independent ECUs being electrically connected to said control unit.
According to yet another embodiment, the marine propulsion control system further comprises a steering control instrument for providing said control unit with an input command. Thereby, the operator can easily provide input commands to the control unit, so that the control unit can control the propulsion units in a direction desired by the operator.
Preferably, the inventive control system forms part of a marine vessel, further comprising a first propulsion unit, a second propulsion unit, a third propulsion unit, a fourth propulsion unit, wherein each propulsion unit being carried by a hull.
The effects of a vessel as described above are largely analogous to the effects of a marine propulsion control system as described above. By providing a vessel with a marine propulsion control the sway movement, does not have to rely on inertia from an earlier sway operation when achieving a yaw. Instead, both a sway and a yaw thrust can be provided at the same time by separating the control of the propulsion units in two channels, where one channel comprises commands for achieving the vessel to sway, and the other channel comprises commands for achieving the vessel to yaw. Each of the channels comprising control commands for at least two propulsion units. A vessel according to above vastly facilitates the control of the vessel.
According to a second aspect of the present inventive concept, a method for controlling a set of propulsion units carried by a hull of a vessel, wherein said set of propulsion units comprise a first a second, a third, and a fourth propulsion unit, said method comprising receiving an input command from a steering control instrument operating the vessel, determining a desired delivered thrust, gear selection and steering angle for said first, second, third and fourth propulsion unit respectively, based on the input command, providing a set of control commands for controlling the desired delivered thrust, gear selection and steering angle for said first, second, third and fourth propulsion unit, and simultaneously providing at least a first control command to said first and fourth propulsion units and a second control command to said second and third propulsion units, if said input command simultaneously indicates a sway and yaw input command, wherein said first control command is adapted to achieve a sway movement of the marine vessel and said second control command is adapted to achieve a yaw movement of said marine vessel.
The effects of a vessel as described above are largely analogous to the effects of a marine propulsion control system, and a vessel as described above. By providing the method to control the set of propulsion units sway movement does not have to rely on inertia from an earlier sway operation when achieving a yaw. Instead, both a sway and a yaw thrust can be provided at the same time by separating the control of the propulsion units in two channels, where one channel comprises commands for achieving the vessel to sway, and the other channel comprises commands for achieving the vessel to yaw. Each of the channels comprising control commands for at least two propulsion units. The method according to above vastly facilitates the control of a vessel.
According to a third aspect of the present invention there is provided a computer program product comprising a computer readable medium having stored thereon computer program means for causing a control unit to control a set of propulsion units carried by a hull of a vessel, wherein said set of propulsion units comprise a first, a second, a third, and a fourth propulsion unit, wherein the computer program product comprises code for receiving an input command from a steering, control instrument operating the vessel, code for determining a desired delivered thrust, gear selection and steering angle for said first, second, third and fourth propulsion unit respectively, based on the input command, code for providing a set of control commands for controlling the desired delivered thrust, gear selection and steering angle for said first, second, third and fourth propulsion unit, and code for simultaneously providing at least a first control command to said first and fourth propulsion units and a second control command to said second and third propulsion units, if said input command simultaneously indicates a sway and yaw input command, wherein said first control command is adapted to achieve a sway movement of the marine vessel and said second control command is adapted to achieve a yaw movement of said marine vessel.
The control is preferably a micro processor or similar device, and the computer readable medium may be one of a removable nonvolatile random access memory, a hard disk drive, a floppy disk, a CD-ROM, a DVD-ROM, a USB memory, an SD memory card, or a similar computer readable medium known in the art. The effects of a the computer product implementation of the invention for controlling a set of propulsion units b a control unit as described above are largely analogous to the effects of a marine propulsion control system, vessel and method as described above.
Furthermore, a code for controlling a set of marine propulsion units allows a user to upgrade an existing marine propulsion control system that allows separate individual control of the steering angle, thrust level and gear selection of the set or propulsion units. With abovementioned code, the upgrade could be done carried out with merely software alterations, vastly reducing the costs for a vessel owner to upgrade the marine propulsion control system.